Apple has confirmed that some iPhone 5 smartphones have defective sleep/wake/power buttons and on Friday kicked off a free component replacement program in the U.S. and Canada.

Devices made through March 2013 may be affected

Apple on Friday confirmed that some iPhone 5 smartphones have defective sleep/wake/power buttons and kicked off a free component replacement program in the U.S. and Canada.

The sleep/wake/power button is on the upper-right top of the iPhone.

"Apple has determined that the sleep/wake button mechanism on a small percentage of iPhone 5 models may stop working or work intermittently," Apple said in an online support document published Friday.

The iPhone 5 debuted in September 2012. Devices made through March 2013 may be affected.

Complaints about the sleep/wake/power button appeared on the Apple support forum just a few months after the iPhone 5 launched, with many customers reporting intermittent issues, or that they had to press the button extremely hard for it to register. The new program covers all eligible iPhone 5 smartphones, including those now out of warranty.

Customers can determine whether their iPhone 5 is eligible for repair by entering its serial number in a field on the support document. The iPhone 5 serial number can be found by tapping the Settings icon, then General and About.

Defective sleep/wake/power buttons are not replaced at Apple's retail stores, but owners can drop off devices there. Alternately, iPhone 5 users can ship their handsets directly to an Apple repair center after calling the Cupertino, Calif. company and requesting a postage-paid box. According to messages posted Saturday on Apple's support forum, customers who took their phones to an Apple store were told that it would be returned in about a week.

iPhone 5 16GB loaners are available, Apple said, and several owners confirmed that they had been handed one. Smartphones still running iOS 6 will be upgraded to iOS 7 by Apple has part of the button replacement.

The program will be expanded to other countries in May, and will expire September 21, 2014, two years after the iPhone 5 first went on sale.